Analysis - Finance Minister Grant Robertson is pitching today's Budget as one that will set the foundations for the government's plan to make the economy more sustainable.

Mr Robertson said the government can't fix everything in one Budget, but health, education, and housing will finally get the support they deserve.

It will invest $42 billion in capital spending over the next five years, in hospitals and schools and other critical public services.

Health is likely to be the biggest winner, with Labour having talked up the sector being underfunded under National.

Hospital buildings blighted with rot, mould and asbestos making headlines] has helped fuel Labour's narrative that the sector has been neglected.

All the noises out of the Beehive point towards health getting a sizeable boost, but expect some areas to be subject to phased-in or delayed spending, to be able to meet the demands.

There has also been a lot of talk from the government about buildings in the education sector being in a poor state.

Education Minister Chris Hipkins estimated it would cost about $166 million to deal with them, which he argued could not all be done this year, meaning the funding would have to be spread over the next four years.

There are also promises set out in the coalition agreement like offering free driving training to all secondary students and restoring funding for gifted students, and there are hints of specific announcements in the early childhood sector.

Housing is the third area likely to be a big focus - with the government already putting on record it will invest $2 billion in its KiwiBuild programme to build 100,000 affordable houses over the next decade, though whether $650,000 is affordable has been the subject of much debate this week.

More funding for state housing is also on the cards, with the waiting list for the homes hitting an all time high - headlines the coalition government will want to avoid.

So how will it all unfold today?

At 10.30am journalists, economists and other analysts will be locked into the Banquet Hall at Parliament and copies of the budget will be distributed and pored over.

Mr Robertson will make a speech in the lockup and take questions, before heading back to his Beehive office to have his budget day snack (note: it's not going to be a pie like the former Finance ministers, Steven Joyce and Bill English).

Mr Robertson will then head to the debating chamber with Prime Minister Jacinda Ardern to start his budget speech at 2pm - the same time that the Banquet Hall doors are unlocked and journalists begin reporting the contents of the 2018 Budget.

Related Stories

Analysis - The Labour party hammered the previous government on housing, accusing them of presiding over a crisis of rising. But can the government keep its promises on housing? Patrick O'meara asks. Audio